Process for the manufacture of soluble metallic fluorides and particularly of beryllim fluoride



Patented Jan. 31, 1939 UNITED STATES PATENT OFFIQE PROCESS FOR THE MANUFACTURE SOLUBLE METALLIC FLUORIDES OF AND PARTICULARLY 0F BERYLLIUM FLU- ORIDE No Drawing. Application October 8, 1937, Serial No. 168,005. In Italy October 26, 1936 19 Claims.

This invention relates to a process for the manufacture of soluble metallic fluorides, and particularly of beryllium fluoride.

The most recent processes known hitherto for the industrial manufacture of beryllium compounds and metallic beryllium are based on the production by treatment of the ore by various processes, of solutions of fluorine compounds of beryllium such as sodium fluoberyllate NazBeFi.

Thus certain authors have proposed the treatment of the ore by means of sodium fluosilicate, which, by baking with the ore at a suitable temperature, with subsequent lixiviation, sometimes with the ulterior addition in solution of sodium fluoride, permits of the final production of a solution of sodium fluoberyllate. It is however known that this salt is of only very low solubility; it therefore results that the volume of the solution necessary for industrial treatment of beryllium ores is enormous, for example for 1 ton of ore corresponding to about l00-120 kgs. of oxide there are required not less than 17,000 to 18,000 litres of Water.

According to a very recent patented process of the applicant, practically the whole of the beryllium is extracted from its ores by means of a reagent containing fluorine advantageously comprising or providing the group (HF) and in this case there is no need of any ulterior addition of sodium fluoride. It is true that in general, in view of the low solubility of the fluoberyllate obtained, very considerable volumes of water are needed.

Whatever is the process which is used for obtaining beryllium fluoride from the diluted solution of sodium fluoberyllate, it is always necessary to pass through the oxide of beryllium, since the complex fluoberyllate anion (BeF) is, as it is well known, of the type of the complex anions which are extremely stable such as the fluosilicic anion or the fluoboric anion. It is thus necessary, after having obtained the oxide, to cause hydrofluoric acid to react in order to obtain the fluoride. The outcome is an expensive operation with the risk of liberation of toxic gases and not leading itself to the production of anhydrous beryllium fluoride which is free of oxide, since with the means which ,re known heretofore oxi-fluoride is always produced. Now, for certain uses, chiefly for the preparation of metalic beryllium and for the production of beryllium alloys, beryllium fluoride can only give good results when it is anhydrous and free of oxide.

The present invention has for its object a process which has none of the above mentioned inconveniences and with which it is possible directly to obtain, from the fritted fluorine compound resulting from the treatment of a beryllium ore by one of the above mentioned processes, a concentrated solution beryllium fluoride which is free of alkaline compounds and of metallic impurities, and from which then pure and anhydrous beryllium fluoride can be separated.

For this purpose, this process is characterized in that after having treated the beryllium ore in the hot by a reagent which causes the beryllium to pass to the condition of a fluorine compound, more particularly by burning the ore either with a fluorinated reagent comprising or providing the group (HF), such as, for instance, an acid fluoride, or with a fluo-silicate, silicon fluoride in solution in an organic solvent of the beryllium fluoride is caused to act on the mass resulting from this treatment, the said solvent being preferably miscible with water but having no dissolving properties with respect to silica, fluo-silicates, alkaline compounds and metallic oxides.

The silicon fluoride forms, in a manner which is known per se, with the bases contained in the treated frit, fluo-silicates which are all practically non-soluble, by liberating the soluble beryllium fluoride. Due to the fact that, according to the invention, silicon fluoride in solution in an organic solvent of the beryllium fluoride is used, the latter is dissolved in situ, which insures its immediate separation, in the form of a solution, from the reaction medium. Furthermore, the process according to the invention offers the advantage that it necessitates only the working of comparatively reduced total volume of materials, the volume of the solution which contains the beryllium fluoride being such that it does not exceed two to two and a half times the volume of the mass resulting from the preparatory treatment of the ore.

Preferably, the silicon fluoride which is used is the silicon tetrafluoride, although the invention does not exclude the use of the polymers of this fluoride. In the case when the treated ore is, for instance, beryl and when this ore is decomposed by means of an acid fluoride, in order finally to treat it by silicon tetrafluoride in solution in an organic solvent, the reactions are as follows:

The beryllium fluoride is collected in solution in the organic solvent in which neither the sodium fluosilicate nor the other compounds present are soluble.

The solution of silicon fluoride in an organic solvent can be prepared in advance and introduced as such into the mass resulting from the previous treatment of the ore, or it can be formed in the Very middle of this mass. More particularly, the silicon fluoride which is necessary can be extracted by all known processes, such as, for instance, by the action of a strong acid such as sulphuric acid, from the residue of the ore remaining after the elimination of the beryllium fluoride in a preceding operation, or it can be formed in a similar manner in the mass from which the beryllium fluoride is to be separated. In the case when the solution of the silicon fluoride is formed inside of the mass to be treated, the silicon fluoride can be introduced into the said mass in a gaseous condition or dissolved in water or other solvents, alone or mixed together, and the organic solvent can be added to a first product of lixiviation in water.

As organic solvent for the silicon fluoride, alcohol as, for instance, ethyl or methyl alcohol or acetone or, in a general manner, any other organic solvent which satisfies the above mentioned conditions can be used. Although the presence of water in the reaction is not indispensable, it is advantageous that a certain proportion of water is added to the organic solvent, in order to avoid that too large a proportion of this latter remains bound to the mass which is exhausted in beryllium fluoride. However, the use of too large a proportion of water would be likely, in spite of the comparative insolubility of the fluosilicates produced by the action of the fluoride of silicon, to carry into solution a certain quantity of the said bodies. Thus it will be advisable, generally speaking, that the proportion of Water does not exceed 50% of the mixture: water+organic solvent.

The solution of beryllium fluoride which has been obtained in the above mentioned manner can be purified and freed from the impurities which it contains, such as traces of metals present in the ore or introduced by the apparatus in which the reaction is effected, for instance by means of air which is caused to pass through the solution at ordinary temperature, which insures the oxidation of these elements. After filtration of this solution and evaporation of the organic solvent, a very concentrated solution of beryllium fluoride in a very pure condition is obtained.

Pure and anhydrous beryllium fluoride can be obtained from this concentrated solution in several manners.

It is more particularly possible, according to the invention, to treat the concentrated solution of beryllium fluoride in a cold condition by means of ammonia or another precipitating agent which is able to free ammonia under the conditions of the treatment, so as to bind part of the beryllium fluoride in the form of ammonium fluoberyllate and to precipitate the other part of the beryllium fluoride in the form of beryllium hydroxide, the said precipitation being accompanied with a freeing of the fluorine which impedes the hydrolysis of the so treated solution. By evaporation and drying of the residue one obtains finally, on the one hand, beryllium hydroxide and, on the other hand, ammonium fluoberyllate in the condition of a salt, which is perfectly well suited for the extraction of anhydrous beryllium fluoride which can be used directly for obtaining metallic beryllium or beryllium alloys. Furthermore, the ammonium fluoberyllate gives as a by-product ammonium fluoride which can be re-used, if necessary, for the production of another fluoride or from which the ammonia which is necessary for the treatment can be regenerated. The quantity of ammonia which is used can vary according as it is desired to obtain more or less beryllium hydroxide.

The concentrated solution of beryllium fluoride can also be submitted to a drying operation through an intense heating in an evaporation apparatus in an atmosphere of gaseous hydrofluoric acid, so as to collect directly all the beryllium in the state of anhydrous fluoride which is free of oxide, without there being any risk of decomposition and of oxidation. The evaporation apparatus which is used will be made preferably of materials which are not attackable by hydrofluoric acid, as for instance silver or preferably fluorspar. It is possible to work through introducing the hydrofluoric acid in a gaseous condition such as is produced by distillation, while progressively increasing the temperature in the interior of the apparatus until it reaches a maximum value of 450 to 600 C. All the gaseous hydrofluoric acid which has been introduced is regenerated by any one of the known processes on the leaving side of the evaporation apparatus. The beryllium fluoride which is obtained in a dry condition can be cooled by a flow of inert gas (such as, for instance, carbon dioxide). It contains practically the whole of the beryllium contained in the original ore.

Although the above description principally relates to the case of the beryllium fluoride, it is, of course, to be understood that the process according to the invention is equally well suited for obtaining generally soluble metallic fluorides in combination, or not, with the beryllium fluoride. It is obvious, indeed, that the treatment of the silicon fluoride in solution, which forms the essential feature of the invention, permits of the separation of any soluble metallic fluoride from the mass resulting from the treatment of an ore of the corresponding metal by a fiuorinating 'reaction which comprises or gives the group (HF), due to the putting in solution of the said fluoride in the organic solvent and to the simultaneous precipitation of the non-soluble fluosilicates obtained by the action of the silicon fluoride on the bases present in the treated ore.

There are given below by way of simple indications which are in no way limiting, two examples of carrying out the process of the present invention as above described.

Example 1 2 tons of beryllium ore after baking, containing 12.50% of BeO are treated by means of 15-16 hectolitres of saturated solution of silicon fluoride in water containing methyl alcohol (which could likewise be replaced by ethyl alcohol) containing dissolved 145 kgs. of silicon tetrafluoride. The admixture is efiected by triturating the semisolid mass in a ball mill for 7--8 hours at ordinary temperature. On coming from the mill the mixture is poured into an agitator into which is blown a current of cold air. The stirring of the mass at low temperature is continued for several hours and the whole is finally filtered on a filter press. The residue in the filter press comprises the ore remaining after the removal of the beryllium and the whole of the initial salts derived in particular from the fluosilicates present. This residue consists of a mixture quite suitably constituted for the manufacture of enamels.

The solution containing the beryllium is then introduced into an ordinary rectification column for the alcohol from which the alcohol is collected in a proportion of 98-99% of the quantity introduced and there is obtained a residual solution comprising pure beryllium fluoride. This solution of beryllium fluoride, about 18-19 hectolitres, is then mixed with concentrated ammonia in the proportion of about 400 kgs., the ammonia employed being of 22 B. The paste is agitated in the cold for several hours then filtered on a filter press and there are added to the first filtrate two Wash liquors from hot water washing of the residual cakes of oxide.

The solution obtained is evaporated in an open dish and then used for the manufacture of anhydrous beryllium fluoride suitable for use for metallurgical operations. There is thus obtained, after drying, in addition to beryllium oxide in a quantity of 50 kgs., anhydrous beryllium fluoride suitable for metallurgical purposes in a quantity of 130 kgs. and also ammonium fluoride in a quantity of 75 kgs.

Example 2 There are treated as in Example 1, 2 tons of beryllium ore after baking containing 12.50% of BeO, but this time by means of -16 hectolitres of a saturated solution of silicon fluothe mixture by means of cold air and filtration and then after evaporation of the organic solvent which is completely recovered, the concentrated solution thus collected is introduced into an apparatus for evaporation and concentration adapted to the nature of the operation, of the capacity of 400 litres in the example given. This solution is there evaporated at a temperature of loo-115 C. adding more solution as it is evaporated. When the whole of the liquid has been introduced and the solution is completely concentrated there is introduced gaseous hydrofluoric acid, first slowly in order to moderate the evolution of heat and then the introduction of the acid gas is increased gradually in such a manner as to cause it to bubble in the mass. From this moment the temperature is raised in a continuous manner to about 500 C. at the end of the operation. At this point the supply of hydrofluoric acid gas is interrupted and an inert gas is introduced, in the example in question carbon dioxide, then the whole is allowed to cool before opening the apparatus in order to remove the beryllium fluoride contained therein. By working under the above conditions there are obtained about 225 kgs. of beryllium fluoride anhydrous and :free from oxide.

What I claim is:

1. A process for obtaining beryllium fluoride from beryllium ore, which comprises treating the ore in the hot with a fluorinated reagent which causes the beryllium to pass into the state of a fluorinated compound and causing to act on the mass resulting from this treatment silicon fluoride in solution in an organic solvent for the beryllium fluoride but having no dissolving properties with respect to silica, fluo-silicates, alkaline compounds and metallic oxides, to immediately separate, in the form of a solution, the beryllium fluoride liberated by the action of the silicon fluoride.

2. A process for obtaining beryllium fluoride from beryllium ore, which comprises treating the ore by burning it with a fluorinated reagent comprising the group (HF) and causing to act on the mass resulting from this treatment silicon fluoride in solution in an organic solvent for the beryllium fluoride, but having no dissolving properties with respect to silica, fluo-silicates, alkaline compounds and metallic oxides, to immediately separate, in the form of a solution, the beryllium fluoride liberated by the action of the silicon fluoride.

3. A process for obtaining beryllium fluoride from beryllium ore, which comprises treating the ore by burning it with a fluorinated reagent which gives the group (HF) and causing to act on the mass resulting from this treatment silicon fluoride in solution in an organic solvent for the silicon fluoride but having no dissolving properties with respect to silica, fluo-silicates, alkaline compounds and metallic oxides, to immediately separate, in the form of a solution, the fluoride of beryllium liberated by the action of the silicon fluoride.

.4. A process for obtaining beryllium fluoride from beryllium ores, which comprises treating the ore by burning it with an acid fluoride and causing to act on the mass resulting from this treatment silicon fluoride solution in an organic solvent for the beryllium fluoride but having no dissolving properties with respect to silica, fluosilicates, alkaline compounds and metallic oxides to immediately separate, in the form of a solution, the beryllium fluoride liberated by the action of the silicon fluoride.

5. A process for obtaining beryllium fluoride from beryllium ores, which comprises treating the ore by burning it with an acid fluoride and causing to act on the mass resulting from this treatment silicon tetrafluoride in solution in an organic solvent for the beryllium fluoride but having no dissolving properties with respect to silica, lino-silicates, alkaline compounds and metallic oxides to immediately separate, in the form of a solution, the beryllium fluoride liberated by the action of the silicon fluoride.

6. A process for obtaining beryllium fluoride from beryllium ore, which comprises treating the main the hot with a fluorinated reagent which causes the beryllium to pass into the state of a fluorinated compound and causing to act on the mass resulting from this treatment silicon fluoride in solution in an organic solvent for the beryllium fluoride miscible with water, but having no dissolving properties with respect to silica, fluo-silicates, alkaline compounds and metallic oxides, to immediately separate, in the form of a solution, the beryllium fluoride liberated by the action of the silicon fluoride.

'7- A process for obtaining beryllium fluoride from beryllium ore, which comprises treating the ore in the hot with a fluorinated reagent which causes the beryllium to pass into the state of a fluorinated compound and causing to act on the mass resulting from this treatment silicon fluoride in solution in a mixture of Water and of an organic solvent for the beryllium fluoride misstble with water, but having no dissolving properties with respect to silica, fluosilicates, alkaline compounds and metallic oxides to immediately separate, in the form of a solution, the beryllium fluoride liberated by the action of the silicon fluoride.

8. A process for obtaining beryllium fluoride from beryllium ore, which comprises treating the ore in the hot with a fluorinated reagent which causes the beryllium to pass into the state of a fluorinated compound and introducing into the mass resulting from this treatment a solution of silicon fluoride in an organic solvent for the beryllium fluoride but having no dissolving properties with respect to silica, fluo-silicates, alkaline compounds and metallic oxides, to immediately separate, in the form of a solution, the beryllium fluoride liberated by the action of the silicon fluoride.

9. A process for obtaining beryllium fluoride from beryllium ore, which comprises treating the ore in the hot with a fluorinated reagent which causes the beryllium to pass into the state of a fluorinated compound and forming in the mass resulting from this treatment a solution of silicon fluoride in an organic solvent for the beryllium fluoride, but having no dissolving properties with respect to silica, fluo-silicates, alkaline compounds and metallic oxides, to immediately separate, in the form of a solution, the beryllium fluoride liberated by the action of the silicon fluoride.

10. A process for obtaining beryllium fluoride from beryllium ore, which comprises treating the ore in the hot with a fluorinated reagent which causes the beryllium to pass into the state of a fluorinated compound, lixiviating the mass resulting from this treatment with water and introducing into the product of this lixiviation silicon fluoride in a gaseous condition and an organic solvent for the beryllium fluoride, miscible with water, but having no dissolving properties with respect to silica, fluosilicates, alkaline compounds and metallic oxides, to immediately separate, in the form of a solution, the beryllium fluoride liberated by the action of the silicon fluoride.

1.A process for obtaining beryllium fluoride from beryllium ore, which comprises treating the ore in the hot with a fluorinated reagent which causes the beryllium to pass into the state of a fluorinated compound, and causing to act on the mass resulting from this treatment silicon fluoride in solution in ethyl alcohol, to immediately separate, in the form of a solution, the beryllium fluoride liberated by the action of the sodium fluoride.

12. A process for obtaining fluoride beryllium from beryllium ore, which comprises treating the ore in the hot with a fluorinated reagent which causes the beryllium to pass into the state of a fluorinated compound, and causing to act on the mass resulting from this treatment silicon fluoride in solution in methyl alcohol, to immediately separate, in the form of a solution, the beryllium fluoride liberated by the action of the silicon fluoride.

3. A process for obtaining beryllium fluoride from beryllium ore, which comprises treating the ore in the hot with a fluorinated reagent which causes the beryllium to pass into the state of a fluorinated compound, and causing to act on the mass resulting from this treatment silicon fluoride in solution in acetone, to immediately separate, in the form of a solution, the beryllium fluoride liberated by the action of the silicon fluoride.

14. A process for obtaining beryllium fluoride from beryllium ore, which comprises treating the ore in the hot with a fluorinated reagent which causes the beryllium to pass into the state of a fluorinated compound and causing to act on the mass resulting from this treatment silicon fluoride in solution in an organic solvent for the beryllium fluoride but having no dissolving properties with respect'to silica, fluo-silicates, alkaline compounds and metallic oxides, to immediately separate, in the form of a solution, the beryllium fluoride liberated by the action of the silicon fluoride, thentreating the so obtained solution of beryllium fluoride by means of a flow of air at the ordinary temperature, filtering it and submitting it to a treatment which causes the evaporation of the organic solvent.

15. A process for obtaining beryllium fluoride according to claim 14, in which the product obtained after the evaporation of the organic solvent is treated by means of ammonia in order to bind part of the beryllium fluoride in the form of ammonium fluo-beryllate and to precipitate the other part of the beryllium fluoride in the form of beryllium hydroxide after which the solution of ammonium fluo-beryllate which hasbeen obtained is submitted to a filtering operation, toan evaporation, and the residue is submitted to a drying operation and treated, in order to obtain pure and anhydrous beryllium fluoride simultaneously with ammonium fluoride.

16. A process for obtaining beryllium fluoride according to claim 14, in which the product obtained after the evaporation of the organic solvent is treated by means of an agent which is able to free ammonia so as to bind part of the beryllium fluoride in the form of ammonium fluoberyllate and to precipitate the other part of the beryllium fluoride in the form beryllium hydroxide, after which the solution of ammonium fluo-beryllate which has been obtained is submitted to a filtering operation, to an evaporation, and the residue is submitted to a drying operation and treated in order to obtain pure and anhydrous beryllium fluoride simultaneously with ammonium fluoride.

17. A process for obtaining beryllium fluoride according to claim 14, in which the product obtained after the evaporation of the organic solvent is submitted to a drying operation through an intense heating in an evaporation apparatus, in an atmosphere of gaseous hydrofluoric acid, so as to collect all the beryllium fluoride directly in an anhydrous condition and free of oxide.

18. A process for obtaining beryllium fluoride according to claim 14, in which the product obtained after the evaporation of the organic solvent is submitted to a drying operation through an intense heating in an evaporation apparatus, in an atmosphere of gaseous hydrofluoric acid, after which carbon dioxide is introduced into the said evaporation apparatus so as to collect all the beryllium fluoride, directly in the state of anhydrous fluoride free of oxide.

19. A process for obtaining soluble metallic fluorides from the ore of the corresponding metal or metals, which comprises treating the ore with a fluorinated reagent which causes the metal to pass into the state of a fluorinated compound, and causing to act on the mass resulting from this treatment silicon fluoride in solution in an organic solvent for the fluoride which is to be obtained, but having no dissolving properties with respect to silica, fluosilicates, alkaline compounds and metallic oxides, to immediately separate, in the form of a solution, the soluble fluoride liberated by the action of the silicon fluoride.

CARLO ADAMOLI. 

